In oil production, primary operations are frequently ineffective in recovering a substantial proportion of the oil-in-place, often leaving as much as 60 to 80% of the oil as residual. It is common, therefore, to employ so-called secondary and tertiary methods to obtain additional oil. One such secondary or tertiary method involves flooding the producting formation with an oil-displacement fluid, such as water, steam, gases, etc., through one or more injection wells spaced from the producing well. As the leading edge, or front, of the flood fluid progresses through the formation, the oil in the formation is pushed towards the producing well. Where plural injection wells are used, the fluids from neighboring wells may merge to form a combined front, and such combined front may indeed completely surround a producing well.
In general, the geological and fluid properties (saturations, permeabilities, etc.) of hydrocarbonaceous zones cause uneven forward movement of the native or injected fluids. In addition, the extent of uneven fluid movement increases with hydrocarbon recovery, field operations, and type of well pattern used in enhanced recovery operations. Often a formation or reservoir will contain zones of varying degrees of permeability. During a water flood or other recovery method, hydrocarbonaceous fluids will be removed from the higher permeability zone while the lower permeability zone retains hydrocarbonaceous fluids. These retained fluids often cannot be removed without blocking off the zone of higher permeability and diverting the injected fluid to the zone of lower permeability.
Therefore, what is needed is a method for the selective injection of fluids to improve the injectivity profile in multiple zone formations in cased and perforated wells which will provide for blocking off a zone of higher permeability and allow for the production of hydrocarbonaceous fluids from a zone of lower permeability.